<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        body{
            margin: 0;
            padding: 0;
        }
        .container{
            width: 500px;
            height: 500px;
            background-color: aquamarine;
            margin: 0 auto;
            position: relative;
        }
        .box1{
            background-color: pink;
            position: absolute;
            top: 0;
            bottom: 0;
            left: 0;
            right: 0;
            width: 300px;
            height: 300px;
            margin: 0 auto;
        }
        .box2{
            background-color: aqua;
        }
    </style>
</head>
<body>
    <div class="container">
        <span class="box1">1</span>
    </div>
    
    <span class="box2">2</span>
</body>
</html>